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Live food organisms for fish - an overview
MILLEROVÁ, Adéla
Feeding organisms are an important part of the fish's nutrition, they are used not only when foddering fish larvae, but also as a supplementary feed for adult fish. The addition of animal and vegetal ingredients in the feed of fish has a proven effect on their growth, reproduction, condition and the intensity of their coloration. To the group of feeding organisms used in fishkeeping belong protozoans, rotifers, crustaceans, nematodes, oligochaetes, molluscs and insects. A specific group of feeding organisms are algae and cyanobacteria, which are used not only as a supplementary feed for aquarium fish, but also as a food for some feeding organisms, for example rotifers, cladocera and copepods. The individual chapters of the thesis contain information about the usage of these specific organisms in fishkeeping, basic characteristics (size, occurrence, eventually also reproduction), breeding in home conditions (inclusive the list of needed things, advantages, disadvantages and the costs of breeding), also the method of obtaining and preservation of this specific type of nutriment.
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Testování háďátka octového (Turbatrix aceti) a substrátů pro eliminaci olejových látek z povrchové blanky pro raná stádia okouna říčního (Perca fluviatilis)
PŘIBYL, Tadeáš
This thesis evaluates an alternative life food Turbatrix aceti for feeding of European perch in its early life stages and the possibility of oily substances elimination from the surface water layer in perch aquaculture. It is of crucial importance to provide perch live food up to 20 days after hatching. Artemia sp. is commonly used for perch feeding in its early life stages. Five different feeding treatments with six replicates in each treatment were performed. The main investigated parameters were fish survival and growth (weight). Average survival (expressed as the number of fish survived) in each of five feeding treatments were: T 107, A5T1 5 145, A10T10 150, A 196 and A15T5 207. Treatment A and A15T5 were not significantly different. After termination of the experiment, the average weights in mg ? standard deviations after 20 days of rearing in given treatment were: A - 28.0 ? 7.7; T 2.9 ? 1.4; A5T15 4.4 ? 3.3; A10T10 7.4 ? 1.1 and A15T5 - 15.9 ? 2.7. The results indicate that Turbatrix aceti cannot be used for rearing of perch early life stages, since mortality was higher and weight lower than in control group, where Artemia sp. was used as a live food. The second experiment tested the possibility to reduce amount of swim bladder inflation failures in perch intensive aquaculture using several types of surface substrates. Swim bladder inflation rates in each treatment were as follows: O 55%, S 40 %, MT 58 %, ML 38 %, PP 65 %, C 48 %. The treatments were not significantly different from each other. Used surface layer collectors of oily substances have not been proved successful, since the percentage of successfully inflated swim bladders were not different from the control treatment, where no surface layer collector of oily substances was used.
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Methods of rearing the early stages of sturgeon fishes
KAHANEC, Martin
The review "Methods of rearing the early stages of sturgeon fishes" brings in its introductory part an information on current systematics of chondrosteans. It has recently gone through certain amendments upon the development of genetic mapping the fish populations in open waters, as well as the specimens from fish farms. Owing to worldwide- and long-term reduction of stocks of the last populations of chondrostean fishes in open waters, controlled reproduction followed by progeny nursing is the only one real possibility to save chondrosteans. Reproduction of broodstock with incubation of fertilized eggs in fish hatcheries is relatively well managed but the transfer of swimming-up larvae to exogenic feeding is species-specific and very demanding in this group of fish, and frequently attended by remarkable losses of specimens, namely due to high mortality of early stages of fish. The thesis deals with basic currently performed methods of initial feeding of sturgeons. The respective types of live food and artificial feeds which are appropriate and available on the territory of the Czech Republic, are described in details. Furthermore, the thesis brings description of the basic technological parameters of fish farming facilities and technologies, as well as physical and chemical properties of water, which are the essential part of successful rearing the early stages of fish.
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